German Patent Application No. DE 42 17 553 A1 describes a waveguide component having fiber couplings. It comprises a base part of polymeric material and a lid part that is constructed as the negative matrix of the base part. V-guides are provided as fiber-coupling regions at the outer extremities. The mid-section of the base part has a waveguide depression, which is provided with an optically active substance, for example a UV-setting adhesive.
FIG. 1 depicts a similar waveguide component. The fibers to be coupled are pre-aligned (a prealignment fixture). After the core monomer hardens, PMMA cover foils (polymeric cover foils) are glued (polymeric glue) to the substrate exhibiting the same patterns in order to bond the waveguides. For this purpose, a core-monomer adhesive is dripped into the waveguide depressions, squeezed out as a foil less than 1 .mu.m thick and subsequently cured by means of UV or thermal polymerization. Following polymerization, the refractive index of the core polymer is about 5*10.sup.-3 higher, so that, together with the surrounding polymeric substrate, it constitutes a dielectric waveguide. Foils commercially known under the name Mylar (TM) can be stripped off after the core monomer hardens (strip-off covers). These foils must be cut exactly to length with a precision of about +/-10 .mu.m. As shown in FIG. 1, the fibers to be coupled are inserted into the V-guides prior to adhesion of the waveguides and are adhesively bonded to the substrate by the overflowing core monomer.